# ±10 V quick question

#### Tony Elliott

Joined May 8, 2015
158
±10 V

Does this mean 0 to +10 volts or -10 to +10 volts?

#### Lestraveled

Joined May 19, 2014
1,946
±10 V can mean a -10 to +10 range. More often it means a dual power supply, -10V and +10V.

#### paulktreg

Joined Jun 2, 2008
832
Depends on context?

If something was written 100±10 V then it would indicate an allowable voltage range of 90V to 110V.

#### cmartinez

Joined Jan 17, 2007
8,174
±10 V can mean a -10 to +10 range. More often it means a dual power supply, -10V and +10V.
It could also be the excitation range of some devices, like load cells, for instance. But as Paul just said, more context is needed.

Joined Jul 18, 2013
28,484
±10 V
Also used for bi directional analogue servo drive command.
Max.

#### Tony Elliott

Joined May 8, 2015
158
It is based on this text.
LFO out is ± 5V

Its to do with attenuating a sine wave.

#### cmartinez

Joined Jan 17, 2007
8,174
It is based on this text.
LFO out is ± 5V

Its to do with attenuating a sine wave.
It would really help if you posted the whole document

#### Brevor

Joined Apr 9, 2011
297
I would take that as meaning the Low frequency Oscillator swings between +5 and-5 Volts.

#### Tony Elliott

Joined May 8, 2015
158
Here is the instructions, the bit is on the left hand top corner. Its creating a panning circuit using Voltage Controlled Amplifiers. I also need to work out how to how to make a wave 180 degrees out of phase.

#### AnalogKid

Joined Aug 1, 2013
10,943
Based on that, the LFO output is a 10 V peak-to peak sinewve centered about GND. Thus the two peaks are +5V and -5V with respect to GND. The required signal is 0V to 5 V, so that is a 2:1 attenuation. The required output centerpoint is +2.5V, so that is a 2.5V addition or offset. So the total conversion circuit is a gain of 0.5 and an offset of +2.5V.

The two circuits on the left indicate creating the offset by combining a DC voltage with the LFO signal. Another approach is to bias the input to the amplifier at 2.5V and AC couple the LFO signal. This prevents any residual DC in the LFO signal from winding up in the output.

Why are you amplitude-modulating audio with a low frequency sinewave?

ak

#### Lestraveled

Joined May 19, 2014
1,946
................. I also need to work out how to how to make a wave 180 degrees out of phase................
The two op-amp circuits do that for you. One is inverting and the other is non-inverting.

Like AK said, you need a 2.5 Volt reference and work out the resistor values for a gain of .5

#### Tony Elliott

Joined May 8, 2015
158
Based on that, the LFO output is a 10 V peak-to peak sinewve centered about GND. Thus the two peaks are +5V and -5V with respect to GND. The required signal is 0V to 5 V, so that is a 2:1 attenuation. The required output centerpoint is +2.5V, so that is a 2.5V addition or offset. So the total conversion circuit is a gain of 0.5 and an offset of +2.5V.

The two circuits on the left indicate creating the offset by combining a DC voltage with the LFO signal. Another approach is to bias the input to the amplifier at 2.5V and AC couple the LFO signal. This prevents any residual DC in the LFO signal from winding up in the output.

Why are you amplitude-modulating audio with a low frequency sinewave?

ak
I am creating a voltage controlled panning circuit to experiment with space.

#### Lestraveled

Joined May 19, 2014
1,946
Have you been tasked to build this circuit and to work out the details? Is so, do you know how to determine the resistor values for the op-amps?

#### #12

Joined Nov 30, 2010
18,224
I can visualize the result. A stereo signal would seem to move back and forth across the room as one speaker goes from full output to zero and back, while the other speaker goes from zero output to full and back to zero. Bit of a mind-melt, but sometimes that's what you want to do with the art.

For those to whom this is not obvious, I hope I explained it.
In addition, I recommend people withhold judgement about the motives. We do lots of circuits here without deciding if the Thread Poster has good reasons to do them.

#### Tony Elliott

Joined May 8, 2015
158
Have you been tasked to build this circuit and to work out the details? Is so, do you know how to determine the resistor values for the op-amps?
The resistor values are already calculated, this is the VCA I need to use parts of this schematic.

#### Lestraveled

Joined May 19, 2014
1,946
@#12
Sounds like a stereo tremolo, but bigger.

#12

#### #12

Joined Nov 30, 2010
18,224
@#12Sounds like a stereo tremolo, but bigger.
You would have to turn one channel off to reduce this to merely a Tremolo!

#### Lestraveled

Joined May 19, 2014
1,946
You would have to turn one channel off to reduce this to merely a Tremolo!
Yup........bigger......Tremolo on steroids

Maybe the TS should go for a 4 channel panning thingamajig. Remember you can add "middle" channels also.

#### #12

Joined Nov 30, 2010
18,224
Yup........bigger......Tremolo on steroids

Maybe the TS should go for a 4 channel panning thingamajig. Remember you can add "middle" channels also.
That would be so much fun!

#### AnalogKid

Joined Aug 1, 2013
10,943
The resistor values are already calculated, this is the VCA I need to use parts of this schematic.
I know this part. It is a classic from audio console designs in the 80's. Getting the control voltage just right usually takes a couple of trimpots, but it will do what you want. Any other questions?

ak